The present invention relates to a cardiac-assist pump system, and in particular, to such a system having a body-implantable pump which is drivable by magnetic coupling across a body surface.
Body-implantable heart assist devices are employed in the treatment of acute heart conditions in which it is necessary to augment the pumping capacity of the heart. Such devices generally include an inflatable balloon positioned within a circulatory pumping chamber. The pumping chamber may be surgically placed intraaortically, or placed across the heart interaortically. The volume of the pumping chamber is alternately increased and decreased by inflating and evacuating the balloon, causing blood to be pumped through the chamber. The balloon is alternately and recurrently inflated and deflated by a fluid pump located external the body. This pump may be connected to the balloon by a tube that passes, transcutaneously, from pump to balloon.
Because heart-assist devices of this type are simple, lightweight, and can be constructed of biologically inert material, operative and post-operative complications can be minimized. However, a significant disadvantage of the above-described kind of device is the need for a transcutaneous, fluid-carrying tube connecting the implanted heart assist device and the external pump.
Problems associated with transcutaneous tubes are well-known in medicine. It is frequently necessary to employ such tubes in draining infection, or where there is a need to obtain frequent intravenous access, such as in kidney dialysis. Because of susceptability to infection, the wounds surrounding the exiting tube must be kept virtually germ free. Further, the exiting tube must be substantially immobilized against the skin to prevent chronic irritation of the wound. Although certain types of puncturable skin coverings have been developed to protect a transcutaneous wound, the above-described problems of infection and irritation have not been satisfactorily solved to data.
In view of the above, the advantages of a heart-assist pump system which does not employ external wire or tube connections are evident.
It is, therefore, an object of the present invention to provide a simple, efficient body-implantable heart-assist pumping system not requiring transcutaneous wires or tubes.
Specifically, it is an object of the invention to provide a heart-assist pump system which is drivable by magnetic coupling across the surface of the body.
It is yet another object of the invention to provide such a system which is lightweight, constructed of biocompatible material, and relatively inexpensive in manufacture.
The present invention provides a body-implantable bellows-type pump which designed to be connected to a conventional heart-assist device employing an inflatable balloon, as described above. The bellows pump, the balloon and a tube connecting the two form a body-implantable closed system operative to transfer a fluid, such as air, alternately and recurrently between the bellows pump and the balloon. The bellows pump includes a movable pumping wall and a pair of rotary magnetic elements which are coupled thereto by cylindrical cams which effect reciprocation of the bellows pumping wall upon rotation of the magnetic elements. A pair of motor-driven rotary magnetic elements placed close to the surface of a body, are adapted to rotate, by magnetic coupling across such surface, the pump rotary magnetic elements, thus to operate the implanted pump and associated heart-assist device.
These and other objects and features of the present invention all now be more fully described with reference to the following detailed description of a preferred embodiment of the invention and the accompanying drawings.